Exchange-traded funds made up of smaller companies outperformed Tuesday, continuing a winning streak that's lasted several months. The SPDR S&P 600 Small Cap ETF /zigman2/quotes/200749058/composite SLY +2.11% gained 1.3% at midday, compared to a 0.8% gain for the S&P 500 /zigman2/quotes/210599714/realtime SPX +1.49% . The Schwab U.S. Small-Cap ETF /zigman2/quotes/205718070/composite SCHA +2.32% was up 0.9%. The iShares Russell 2000 Growth ETF /zigman2/quotes/202147885/composite IWO +2.83% was up only 0.5%, but like its two competitors, has gained much more in the month to date than the broad index: 7.1%, compared to 2.7% for the S&P 500. In October, the iShares fund was on track for its best month since May; for the other two funds, it would be the best since April. Over the past three months, all three small-cap funds have returned over 10%, compared to just over 6% for the broad market. Investors are embracing smaller companies because in most cases they're less pricey than the giants. In the year to date, for example, only the iShares fund is positive, and its 11% return is less than half that of the Nasdaq Composite /zigman2/quotes/210598365/realtime COMP +2.32% . Bets on smaller companies represent bets that the economy will stay resilient, since smaller firms have less resources to withstand difficult times. That may be a chancier investment decision now than before, with uncertainty around the U.S. presidential election, coronavirus fiscal aid, and much more.